1. Field of the Invention
The present invention relates to a keyswitch device suitable for use in a keyboard device used as an input/output device of, for example, a word processor or a personal computer, and a keyboard device including the keyswitch device.
2. Description of the Related Art
Hereunder, a related X-shaped keyswitch device used in a keyboard device will be described with reference to FIGS. 4 and 5. A mount member 31 is formed of, for example, a metallic plate and comprises a bottom wall 31a, a plurality of relatively long supporting sections 31b, and a plurality of semi-circular arc shaped holding sections 31c. In order to form the supporting sections 31b, cuts are formed in the bottom wall 31a and the cut portions that are joined at two sides are raised. These cut-and-raised portions are disposed side by side and correspond to the supporting sections 31b. In order to form the holding sections 31c, cuts are formed in the bottom wall 31a in a cantilever manner and the cut portions that are joined at one side are raised. These cut-and-raised portions are disposed side by side and correspond to the holding sections 31c, each of which forms a pair with its associated supporting section 31b. A flexible substrate (not shown) having a plurality of stationary contacts is disposed on the top surface of the bottom wall 31a. A movable contact member 33 comprises a cup-shaped movable section 33a, formed of resin or the like, and a contact section 33b, disposed on the upper surface of the inner portion of the movable section 33a. The movable contact member 33, opposing stationary contacts 32, is mounted to the flexible substrate. When the movable section 33a is pushed and moved, the contact section 33b comes into contact with the stationary contacts 32, whereas, when the movable section 33a is released, the movable section 33a returns to its original state by itself, causing the contact section 33b to move out of contact with the stationary contacts 32. A first lever 34 is molded out of synthetic resin and has a U shape. It comprises a pair of arms 34a, a connecting section 34b connected to one end of each arm 34a, and a circular cylindrical engager 34c disposed at the other end of each arm 34a. A second lever 35 is molded out of synthetic resin and has an H shape. It comprises a pair of arms 35a, a connecting section 35b connected to the central portion of each arm 35a, and circular cylindrical engagers 35c and 35d disposed at respective ends of each arm 35a. By positioning the second lever 35 inside the first lever 34 and placing them so that their central portions are aligned, the first and second levers 34 and 35 are rotatably combined in the form of a cross by a rotary shaft 34d, so that the combined form of the first and second levers 34 and 35 has an X-shaped pantograph structure. With the rotary shaft 34d as a fulcrum, the upper sides of the first and second levers 34 and 35 can move vertically. The first and second levers 34 and 35 combined in this manner are mounted to the mount member 31 in the following way. First, as shown in FIG. 4, one end of one arm 35a and one end of the other arm 35a of the second lever 35 are pushed towards each other in the directions of arrows X. With these ends of the arms 35a moved towards each other, the engagers 35c are aligned with their respective holding sections 31c. When, after the alignment, the ends of the arms 35a that have been pushed towards each other in the directions of arrows X are released, the arms 35a return to their original states by themselves, causing the engagers 35c to be engaged inside the respective holding sections 31c. Next, as shown in FIG. 4, one end of one arm 34a and one end of the other arm 34a of the first lever 34 are pushed towards each other in the directions of arrows Y. With these ends of the arms 34a moved towards each other, the engagers 34c are aligned with the respective supporting sections 31b. When, after the alignment, the ends of the arms 34a that have been pushed towards each other in the directions of arrows Y are released, the arms 34a return to their original states by themselves, causing the engagers 34c to be engaged inside the respective supporting sections 31b. In this way, both the first and second levers 34 and 35 are mounted to the mount member 31 with the pairs of arms 34a and 35a in pushed states. When the first and second levers 34 and 35 are mounted to the mount member 31, the movable contact member 33 is positioned below the central portions of the crossing portions of the first and second levers 34 and 35, so that the movable contact member 33 can be pushed by the second lever 35. A keytop 36 is molded out of synthetic resin and has the shape of an inverted boat. It comprises guides 36a and 36b. The guide 36a is a vertical groove disposed at the inner portion of the lower surface of the keytop 36. The guide 36b is a horizontal groove disposed at the inner portion of the lower surface of the keytop 36. The keytop 36 is mounted to and supported by the first and second levers 34 and 35 by fitting the connecting section 34b of the first lever 34 to the guide 36a and fitting the engagers 35d of the second lever 35 to the guide 36b. The one keytop 36 having such a structure, the pair of first and second levers 34 and 35, the movable contact member 33, the stationary contacts 32, and the mount member 31 form one keyswitch device. By disposing a plurality of such keyswitch devices, a keyboard device is formed. Next, the operation of such a related keyswitch device will be given. First, when the top surface of the keytop 26 is pressed, the first and second levers 34 and 35 are pushed, so that, with the rotary shaft 34d as a fulcrum, the first and second levers 34 and 35 are rotated and moved downward. At this time, the engagers 35c of the second lever 35 are rotated while they are held by their respective holding sections 31c, and the engagers 34c of the first lever 34 are slid horizontally while they are supported by their respective supporting sections 31b. At the keytop 36, the engagers 35d of the second lever 35 are slid horizontally inside the guide 36b, and the connecting section 34b of the first lever 34 is slid vertically inside the guide 36a. 
By the downward movement of the first and second levers 34 and 35, the movable section 33a of the movable contact member 33 is pushed downward, causing the contact section 33b to come into contact with the stationary contacts 32, so that the keyswitch device is turned on. Next, when the keytop 36 is released, the movable section 33a returns to its original state, causing the first and second levers 34 and 35 to be pushed back upward. This causes the keytop 36 to move upward, so that the first and second levers 34 and 35 and the keytop 36 return to their original states before being pushed, so that the keyswitch device is turned off.
The keyswitch device having the above-described structure is widely used in, for example, keyboard devices of personal computers. However, size reduction of electronic devices in recent years has resulted in an increased tendency for a demand for smaller and thinner keyswitch devices. However, in the keyswitch device having the structure shown in FIGS. 4 and 5, the rotary shaft 34d serving as the center of rotation of the levers 34 and 35 is at the centers in the lengthwise direction of the levers 34 and 35, the keytop 36 is connected to the top sides of the levers 34 and 35 with the rotary shaft 34d as the center, and the bottom sides of the levers 34 and 35 are connected to the mount member 31, so that, as the levers 34 and 35 are shortened for the purpose of forming a smaller and thinner keyswitch device, a limit in the lengths of the levers 34 and 35 that allow smooth rotation is reached, so that further reduction in size and thickness cannot be achieved. In addition, in the keyswitch device having their levers disposed in the form of an X shape as viewed from a side, when a top peripheral edge of the top surface at a bearing side of the keytop 36 is pressed, the keytop 36 may tilt in directions A and B in FIG. 5, in which case it is pressed without being moved horizontally downward. In such a case, the contact section 33b may not come into contact with the stationary contacts 32 even if the keytop is pressed. Therefore, there is a demand for a keyswitch device which makes it possible to perform a key input operation by reliably causing the contact section to come into contact with the stationary contacts even when a peripheral edge of the top surface of the keytop is pressed by, for example, a finger.
The present invention has been achieved to overcome the aforementioned problems, and has as its object the provision of a keyswitch device which makes it possible to perform a key input operation by reliably causing a contact section to come into contact with a stationary contact even when a peripheral edge of the top surface of a keytop is pressed by, for example, a finger. It is another object of the present invention to provide a keyboard device which comprises the keyswitch device, which can be easily reduced in size, and which can be easily operated.
To these ends, according to one aspect of the present invention, there is provided a keyswitch device comprising a base; a plurality of levers, one side of each lever movably engaging the base; a keytop supported so as to be movable vertically with respect to the base by being engaged with the other side of each lever; and a switch for performing a switching operation when the keytop is moved vertically. In the keyswitch device, rotary shafts for allowing rotation of the respective levers within respective rotational planes are disposed at respective engagers at both sides of the levers. One of the engagers at each lever is a first engager for movably supporting one of the rotary shafts at the base or the keytop. The other engager at each lever is a second engager for rotatably supporting the other rotary shaft. The plurality of levers comprise a first lever, a second lever, and a third lever. The rotary shafts or rotary shaft lines of the first and second levers cross the rotary shafts of the third lever. The engagers at the keytop side at the first and second levers are the first engagers for movably engaging the rotary shafts of the first and second levers in a guide groove in the keytop.
In other words, unlike the related keyswitch device in which two levers are such that a shaft is fixed at the location where they cross, the levers independently engage the base and the keytop, and the rotary shafts of at least one lever are disposed so as to cross the rotary shafts of another lever. By virtue of such a structure, even if the lengths of the levers are reduced for reducing the size and thickness of the keyswitch device, the operability of the keyswitch device at the time of a key input operation is not impaired, and the keyswitch device can be more easily reduced in size and thickness than the related keyswitch device having an X-shaped supporting structure.
When a peripheral edge of the top surface of the keytop is pressed at the time of a key input operation, the keytop is not moved downward in a tilted state, but is moved downward in a substantially horizontal state. For example, if the case of supporting the keytop by two levers is considered, when, as in the related keyswitch device, the rotary shafts at the keytop side of these levers are disposed parallel to each other, the keytop can tilt in a direction perpendicular to these rotary shafts. However, in the structure of the present invention, tilting of the rotary shafts of one of the levers in the direction of rotation of the rotary shafts is restricted by the other lever whose rotary shafts cross these rotary shafts, so that the keytop is moved vertically in a horizontal state. Therefore, according to the keyswitch device of the present invention, rattling of the keytop in the horizontal direction can be prevented from occurring, and the keytop is moved vertically without being tiled, so that the switch can reliably perform a switching operation at the time of a key input operation.
Another structure may be used for the keyswitch device. Here, the keyswitch device comprises a base; a plurality of levers, one side of each lever movably engaging the base; a keytop supported so as to be movable vertically with respect to the base by being engaged with the other side of each lever; and a switch for performing a switching operation as the keytop is moved vertically. In the keyswitch device, rotary shafts for allowing rotation of the respective levers within respective rotational planes are disposed at respective engagers at both sides of the levers. One of the engagers at each lever is a first engager for movably supporting one of the rotary shafts at the base or the keytop. The other engager at each lever is a second engager for rotatably supporting the other rotary shaft. The plurality of levers comprise a first lever, a second lever, and a third lever. The rotary shafts or rotary shaft lines of the first and second levers cross the rotary shafts of the third lever. The engagers at the keytop side at the first and second levers are the second engagers for rotatably engaging the rotary shafts of the first and second levers in a guide groove in the keytop. Even with this structure, advantages similar to those of the keyswitch device of the one aspect are provided.
In a first form, the plurality of lever members each comprise a pair of arms and at least one connecting section connecting the arms, and each have a U shape or a frame shape in plan view, and the rotary shafts are disposed at respective sides of the arms. According to this structure, the switch can be surrounded by the levers without reducing the supporting strength of the key top by the levers.
In a second form, when the structure of the one aspect is used, the rotary shaft at the keytop side of the third lever is disposed below the rotary shafts at the keytop side of the first and second levers. According to this structure, by disposing the third lever whose rotary shafts cross the rotary shafts of the first and second levers below the first and second levers, space below the keytop can be effectively used, so that the keyswitch device can be easily reduced in thickness and size.
In a third form, when the structure of the first form is used, the first and second levers are each sandwiched at a pair of hook-shaped rotary bearings disposed at the base engaging the first and second levers, and the positions of the first and second levers in the lengthwise directions of the rotary shafts of the first and second levers are restricted by the respective pairs of hook-shaped rotary bearings. According to this structure, movements of the first and second levers in the directions of the rotary shafts are restricted, so that rattling of the keytop can be effectively restricted.
In a fourth form, when the structure of the first form is used, the third lever is sandwiched at and engaged with a pair of hook-shaped slide bearings disposed at the base, and the position of the third lever in the lengthwise direction of the rotary shaft is restricted by the hook-shaped slide bearings. According to this structure, movement of even the third lever in the directions of the rotary shafts can be restricted, so that rattling of the keytop can be further restricted.
In a fifth form, when the structure of the first form is used, the keytop and the third lever are engaged by engagement of a rotary bearing of the keytop and the shaft of the third lever, and the position of the rotary bearing is restricted by being sandwiched by the pair of arms of the third lever. According to this structure, the positions of the keytop and the third lever are restricted, so that rattling of the keytop can be more effectively restricted.
In a sixth form, when the structure of the one aspect is used, the keytop comprises a holder engaging each lever and a key cap adhered to the holder. By virtue of such a structure, since the structural members, including the holder, the levers, and the base, can be used as common members regardless of the type of key cap, a keyswitch device which has a wide range of application and which can allow easy replacement of, for example, the key cap can be provided.
In a seventh form, when the structure of the sixth form is used, the shafts at the keytop side of the first and second levers are sandwiched by a recessed portion of the holding member, where the guide groove for movably supporting the shafts is disposed, and the key cap adhered to the holder. By virtue of such a structure, the first and second levers can be easily engaged with the keytop, so that the keyswitch device can be easily assembled. Since the rotary shafts of the first and second levers are sandwiched by the key cap and the holder, the rotary shafts and the key cap are always kept parallel, so that tilting of the key cap occurs even less frequently.
According to another aspect of the present invention, there is provided a keyboard device comprising any one of the above-described keyswitch devices. The keyboard device comprising the keyswitch device of the present invention can be easily reduced in size and thickness and is such that the keytop of the keyswitch device can be moved vertically in a constantly horizontal state. Therefore, when the keyswitch device is pressed, a key input operation can be reliably performed, so that a keyboard having excellent operability can be provided.